1. Field of the Invention:
The present invention relates to an apparatus for separating solid matter, and more particularly to a batch-type centrifugal separator which is suited for separating solid matter from one another utilizing the difference in specific gravities.
2. Description of the Prior Art:
Batch-type centrifugal separators have been extensively used as means for separating solid matter from liquids or for separating solid matter from one another. The separators of this type have been based upon either the centrifugal sedimentation method or the centrifugal filtration method. First, these conventional techniques will be described below.
FIG. 1 is a section view of a sedimentation-type centrifugal separator, in which reference numeral 1 denotes an upper end plate of a rotor of the centrifugal separator, 2 denotes a non-perforated hollow cylindrical member, 3 denotes a lower end plate, 4 denotes a drive shaft, 5 denotes a liquid discharge pipe, 6 denotes a liquid discharge pipe driving device, 7 denotes a supply pipe, 8 denotes a scraper, 9 denotes a device for driving the scraper up and down, 10 denotes a device for driving the scraper in the horizontal direction, 11 denotes a solid discharge port, and 12 denotes a fixing rod. Symbols A and B represent a solid matter and a liquid, respectively.
The upper end plate 1 and the lower end plate 3 are united with the hollow non-perforated cylinder 2 to form a rotor as a unitary structure. The drive shaft 4 is connected at its one end to the lower end plate 3 through a plurality of fixing rods 12 and is connected at its other end to a motor which is not shown. The liquid discharge pipe driving device 6, supply pipe 7 and the drive device 10 for driving the scraper in the horizontal direction are fixed to an outer casing which is not shown.
In operation, the liquid discharging pipe 5 and the scraper 8 are moved so as not to come in contact with the liquid surface, and the motor is started to transmit the rotational force of the motor to the rotor through the drive shaft 4. Then, a slurry which is a mixture of the solid matter A and the liquid B is supplied through the supply pipe 7. When the solid matter A has a greater specific gravity than the liquid B, the solid matter A moves toward the outer peripheral region and the liquid B moves toward the inner peripheral region as illustrated. If there is any solid matter having a specific gravity smaller than the liquid B, such a matter moves to the innermost region inside the region of the liquid B. Thereafter, the liquid B is discharged while the liquid discharge pipe 5 gradually moves toward the outer periphery by the operation of the driving device 6. In this case, solid matter having specific gravities smaller than that of the liquid B are discharged together with the liquid B. After the completion of the discharge of the liquid B, the rotor is decelerated and the scraper 8 is moved toward the outer periphery by the horizontally driving device 9 while being moved up and down by the operation of the driving device 10, thereby to scrape the solid matter A. The solid matter is discharged by the force of gravity through the solid discharging port 11.
This sedimentation-type centrifugal separator, however, cannot completely collect the liquid content in the solid matter, although it can make solid-liquid separation and solid-solid separation by the difference in specific gravities. In the case of a liquid other than water, therefore, the solid matter must be washed using another device.
FIG. 2 is a section view of a filtration-type centrifugal separator, in which reference numeral 13 denotes a washing pipe, and 14 designates a hollow perforated cylinder. Other portions are identical to those shown in FIG. 1. These identical portions are designated by corresponding reference numerals and detailed description of such portions is omitted. The washing pipe 13 is fixed to the outer casing together with the supply pipe 7 and a horizontal scraper driving device 10. This filtration-type separator differs from the sedimentation-type separator explained before in that it does not have the liquid discharge pipe 5 and the liquid B is allowed to be discharged to the outside of the rotor through the perforations of the perforated hollow cylinder 14 regardless of the specific gravities of the liquid B and the solid matter A. In addition, it is possible to wash the solid matter A by using the washing pipe 13.
This filtration-type separator, however, cannot hold the liquid B in the rotor, and cannot effect the solid-solid separation by the difference in specific gravities.